U.S. patent application number 15/181914 was filed with the patent office on 2016-12-22 for image processing apparatus, image processing method, and storage medium.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Takuya Shimada.
Application Number | 20160368293 15/181914 |
Document ID | / |
Family ID | 56134063 |
Filed Date | 2016-12-22 |
United States Patent
Application |
20160368293 |
Kind Code |
A1 |
Shimada; Takuya |
December 22, 2016 |
IMAGE PROCESSING APPARATUS, IMAGE PROCESSING METHOD, AND STORAGE
MEDIUM
Abstract
An image processing apparatus of the present embodiment
generates image data representing an image which reproduces
anisotropy. The image processing apparatus of the present
embodiment has a receiving unit configured to receive an input of
image data having anisotropy information and a generating unit
configured to generate a signal corresponding to a printing
material based on the anisotropy information. The generating unit
generates an ejection signal so that a first area and a second area
have different smoothnesses, the first area being formed by the
printing material adjacently ejected in a first direction, the
second area being formed by the printing material adjacently
ejected in a second direction, the second direction being different
from the first direction.
Inventors: |
Shimada; Takuya;
(Kawasaki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
56134063 |
Appl. No.: |
15/181914 |
Filed: |
June 14, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B41J 2/2114 20130101;
H04N 1/54 20130101; B41J 29/38 20130101 |
International
Class: |
B41J 29/38 20060101
B41J029/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 2015 |
JP |
2015-123012 |
Claims
1. An image processing apparatus for generating image data
representing an image which reproduces anisotropy, the image
processing apparatus comprising: a receiving unit configured to
receive an input of image data having anisotropy information; and a
generating unit configured to generate a signal corresponding to a
printing material based on the anisotropy information, wherein the
generating unit generates the signal so that a first area and a
second area have different smoothnesses, the first area being
formed by the printing material adjacently ejected in a first
direction, the second area being formed by the printing material
adjacently ejected in a second direction, the second direction
being different from the first direction.
2. The image processing apparatus according to claim 1, wherein the
generating unit generates the signal so that the first area and the
second area have different smoothnesses by differentiating an
ejection time difference of the printing material adjacently
ejected in the first direction from an ejection time difference of
the printing material adjacently ejected in the second
direction.
3. The image processing apparatus according to claim 2, wherein the
generating unit generates the signal so that the first area forms a
smooth area having a high smoothness, by setting the ejection time
difference of the printing material to be equal to or less than a
threshold.
4. The image processing apparatus according to claim 3, wherein the
generating unit generates the signal so that an aspect ratio of the
smooth area increases as anisotropy indicated by the anisotropy
information increases.
5. The image processing apparatus according to claim 3, wherein the
smooth area is formed by the printing material ejected in a same
scanning of a print head.
6. The image processing apparatus according to claim 3, further
comprising a determination unit configured to determine a
longitudinal direction of the smooth area based on the anisotropy
information.
7. The image processing apparatus according to claim 3, wherein the
smooth area is formed by a specific type of printing material.
8. The image processing apparatus according to claim 3, wherein the
smooth area is formed by a printing material printed on a surface
layer of the image.
9. The image processing apparatus according to claim 1, further
comprising a receiving unit configured to receive a printing
condition setting, wherein the generating unit generates a signal
corresponding to a printing material based on the anisotropy
information and the printing condition.
10. The image processing apparatus according to claim 1, further
comprising a shape data generating unit configured to generate
shape data based on the anisotropy information, wherein the shape
data generating unit generates the shape data so that a first
structure formed in the first direction and a second structure
formed in the second direction have different reflection
intensities corresponding to incident light depending on the
direction.
11. The image processing apparatus according to claim 1, wherein
the anisotropy information includes information specifying: an
azimuth angle at which a reflection intensity of specular reflected
light corresponding to incident light becomes a maximum, a first
specular reflection intensity being the reflection intensity of the
specular reflected light at the azimuth angle, a first reflection
haze being a reflection intensity of diffused light near the
specular reflection direction, a second specular reflection
intensity being the reflection intensity of the specular reflected
light corresponding to the incident light at an angle different
from the azimuth angle, and a second reflection haze being a
reflection intensity of diffused light near the specular reflection
direction.
12. The image processing apparatus according to claim 1, wherein
the anisotropy information includes information specifying a
plurality of gloss mappings.
13. The image processing apparatus according to claim 1, wherein
the anisotropy information includes information specifying a
BRDF.
14. The image processing apparatus according to claim 1, further
comprising a printing unit configured to print the image by
ejecting the printing material on a print medium based on the
signal.
15. The image processing apparatus according to claim 10, further
comprising a printing unit configured to print the image by forming
the structure on a print medium based on the shape data and
ejecting the printing material on an upper surface of the structure
based on the signal.
16. An image processing method for generating image data
representing an image which reproduces anisotropy, the image
processing method comprising the steps of: receiving an input of
image data having anisotropy information; and generating a signal
corresponding to a printing material based on the anisotropy
information, wherein in the generating step, the signal is
generated so that a first area and a second area have different
smoothnesses, the first area being formed by the printing material
adjacently ejected in a first direction, the second area being
formed by the printing material adjacently ejected in a second
direction, the second direction being different from the first
direction.
17. A non-transitory computer readable storage medium storing a
program for causing a computer to function as an image processing
apparatus for generating image data representing an image which
reproduces anisotropy, where the image processing apparatus
comprises: a receiving unit configured to receive an input of image
data having anisotropy information; and a generating unit
configured to generate a signal corresponding to a printing
material based on the anisotropy information, wherein the
generating unit generates the signal so that a first area and a
second area have different smoothnesses, the first area being
formed by the printing material adjacently ejected in a first
direction, the second area being formed by the printing material
adjacently ejected in a second direction, the second direction
being different from the first direction.
Description
BACKGROUND OF THE INVENTION
[0001] Field of the Invention
[0002] The present invention relates to an image processing
apparatus for generating image data representing an image which
reproduces anisotropy, an image processing method, and a storage
medium storing a program for achieving them.
[0003] Description of the Related Art
[0004] Recently, research for the improvement of designs of a print
image has progressed. For example, Xin Tong et al., Bi-Scale
Appearance Fabrication, Transaction on Graphics, Vol. 32, No. 4,
Article 145, 2013 discloses a printing method for printing an image
representing anisotropy, such as different gloss or color, by
forming a structure having a fine inclination on a print medium and
by creating different degrees of scattering of light reflected on a
surface of the structure depending on an illumination
direction.
SUMMARY OF THE INVENTION
[0005] In the above printing method of the Xin Tong et al.,
Bi-Scale Appearance Fabrication, Transaction on Graphics, Vol. 32,
No. 4, Article 145, 2013, an image representing anisotropy, such as
different gloss or color, is printed by forming a structure having
a fine inclination on a print medium and creating different degrees
of scattering of light reflected on a surface of the structure
depending on an illumination direction. Accordingly, if color is
applied to the structure with color ink and the like,
characteristics of the ink may reduce a difference in degrees of
scattering of light depending on an illumination direction, causing
a problem of reduction of anisotropy of a print image.
[0006] The image processing apparatus according to the present
invention is an image processing apparatus for generating image
data representing an image which reproduces anisotropy, the image
processing apparatus including: a receiving unit configured to
receive an input of image data having anisotropy information; and a
generating unit configured to generate a signal corresponding to a
printing material based on the anisotropy information, wherein the
generating unit generates the signal so that a first area and a
second area have different smoothnesses, the first area being
formed by the printing material adjacently ejected in a first
direction, the second area being formed by the printing material
adjacently ejected in a second direction, the second direction
being different from the first direction.
[0007] Further features of the present invention will become
apparent from the following description of exemplary embodiments
(with reference to the attached drawings).
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1A to FIG. 1D are schematic views illustrating
anisotropy;
[0009] FIG. 2A to FIG. 2C are schematic views for explaining a
mechanism for controlling anisotropy by a structure having a
surface roughness shape;
[0010] FIG. 3A and FIG. 3B are schematic views for explaining a
surface structure of a print medium;
[0011] FIG. 4 is a block diagram showing a schematic configuration
of an image printing unit according to a first embodiment;
[0012] FIG. 5A to FIG. 5C are schematic views for explaining
multi-pass printing according to the first embodiment;
[0013] FIG. 6 is a block diagram showing a hardware configuration
of an image printing apparatus according to the first
embodiment;
[0014] FIG. 7 is a flow chart showing an image printing procedure
according to the first embodiment;
[0015] FIG. 8 is a schematic view showing an example of a
conversion table of a total reflected light amount according to the
first embodiment;
[0016] FIG. 9 is a schematic view showing an example of a shape
generation table according to the first embodiment;
[0017] FIG. 10 is a schematic view showing an example of a shape of
a structure according to the first embodiment;
[0018] FIG. 11 is a flow chart showing a procedure for generating a
pass mask according to the first embodiment;
[0019] FIG. 12A to FIG. 12C are schematic views showing an example
of a first pass separation pattern according to the first
embodiment;
[0020] FIG. 13 is a schematic view showing an example of a second
pass separation pattern according to the first embodiment;
[0021] FIG. 14 is a flow chart showing a procedure for generating a
pass mask according to the first embodiment;
[0022] FIG. 15 is a schematic view for explaining a mechanism of
error diffusion according to the first embodiment;
[0023] FIG. 16 is a block diagram showing a functional
configuration of the image printing apparatus according to the
first embodiment;
[0024] FIG. 17 is a view showing an exemplary output image
according to the first embodiment;
[0025] FIG. 18 is a schematic view showing an exemplary UI
according to a modification example 3; and
[0026] FIG. 19 is a block diagram showing a schematic configuration
of an image printing unit according to a second embodiment.
DESCRIPTION OF THE EMBODIMENTS
[0027] Embodiments for carrying out the present invention will be
described with reference to the attached drawings. However,
elements described in the embodiments are only exemplary and are
not intended to limit the scope of the present invention. It should
be noted that the same reference numeral refers to the same element
in the following description.
First Embodiment
Anisotropy
[0028] First, anisotropy will be described. FIG. 1A to FIG. 1D are
schematic views illustrating anisotropy according to the present
embodiment. FIG. 1A shows a reflection characteristic in an x
direction of a sample 100 which exhibits anisotropy, and a curve
101 shows a reflection intensity in each direction when incident
light 102 illuminates toward a point o. For example, the length of
a line oa from the point o to a point a on the curve 101 shows a
reflection intensity of light reflected from the point o toward the
point a. The direction toward the point a at which a reflection
intensity from the point o becomes a maximum is the direction of
specular reflection, and the direction from the point o toward a
point b on the curve 101 is a direction shifted from the direction
of specular reflection by a degrees. At this time, the reflection
intensity from the point o to the point a is also referred to as a
specular reflection intensity, and the reflection intensity from
the point o to the point b is also referred to as a reflection
haze.
[0029] FIG. 1B shows a reflection characteristic in a y direction
of the sample 100 which exhibits anisotropy, and a curve 103 shows
a reflection intensity in each direction when incident light 104
illuminates toward the point o. Note that the y direction is
orthogonal to the x direction. Like FIG. 1A, the length of a line
oc from the point o to a point c on the curve 103 shows a
reflection intensity of light reflected from the point o toward the
point c. The direction toward the point c at which a reflection
intensity from the point o becomes a maximum is the direction of
specular reflection, and the direction from the point o toward a
point d on the curve 103 is a direction shifted from the direction
of specular reflection by a degrees. At this time, the reflection
intensity from the point o to the point c is also referred to as a
specular reflection intensity, and the reflection intensity from
the point o to the point d is also referred to as a reflection
haze.
[0030] The specular reflection intensity in the x direction shown
by the length of the line oa in FIG. 1A is lower than the specular
reflection intensity in the y direction shown by the length of the
line oc in FIG. 1B. The reflection haze in the x direction shown by
the length of the line ob in FIG. 1A is higher than the reflection
haze in the y direction shown by the length of the line od shown in
FIG. 1B. As described, a property that the reflection intensity
corresponding to incident light in the direction of specular
reflection and near the direction of specular reflection changes
depending on the direction of the incident light and an observation
direction is referred to as anisotropy. A high-contrast anisotropy
means that a reflection intensity corresponding to the incident
light greatly changes depending on the direction of the incident
light and the observation direction.
[0031] FIG. 1C and FIG. 1D show examples of the sample 100
including two areas having different reflection characteristics.
Each of a square area 105 and a round area 106 has different
reflection characteristics in the x direction and the y direction.
More specifically, the square area 105 shown in FIG. 1C has the
reflection characteristic shown in FIG. 1A and the round area 106
shown in FIG. 1C has the reflection characteristic shown in FIG.
1B. Meanwhile, the square area 105 shown in FIG. 1D has the
reflection characteristic shown in FIG. 1B, and the round area 106
shown in FIG. 1D has the reflection characteristic shown in FIG.
1A. That is, if rotated by 90 degrees, the sample 100 shown in FIG.
1C corresponds to the sample 100 shown in FIG. 1D.
[0032] FIG. 1C schematically shows a positional relationship among
a direction 107 of incident light, the sample 100, and an
observation direction 108. In FIG. 1C, if the direction 107 of the
incident light and the observation direction 108 are in the
relation of specular reflection, the round area 106 is viewed as
lighter, with a higher gloss, than the square area 105. However, if
the observation direction 108 is shifted by a degrees from the
direction of specular reflection, the square area 105 is viewed as
lighter, with a higher gloss, than the round area 106. That is, if
the sample is viewed from a different position, a light area and a
dark area are reversed.
[0033] FIG. 1D schematically shows a positional relationship among
the direction 107 of the incident light, the sample 100 rotated by
90 degrees from the position of the sample 100 shown in FIG. 1C,
and the observation direction 108. If the direction 107 of the
incident light and the observation direction 108 are in the
relation of specular reflection, the square area 105 shown in FIG.
1D is viewed as lighter, with a higher gloss, than the round area
106. That is, if the direction of the sample is changed, a light
area and a dark area are reversed. As described above, if the
sample is viewed from a different position or the direction of the
sample is changed, a light area and a dark area are reversed in the
sample exhibiting anisotropy. The image printing apparatus
according to the present embodiment generates image data
representing an image having such characteristics.
[0034] Next, a description will be given of a mechanism for
controlling anisotropy by surface roughness. FIG. 2A to FIG. 2C are
schematic views for explaining a mechanism for controlling
anisotropy by surface roughness. FIG. 2A is a view showing an
example of a surface roughness shape of a structure 201
representing anisotropy. FIG. 2B shows a cross section parallel to
a u direction of the structure 201, and FIG. 2C shows a cross
section parallel to a v direction of the structure 201. As shown in
FIG. 2B, the cross section parallel to the u direction is
arc-shaped, and if the structure 201 is irradiated with light 202
in an arrow direction, surface reflected light 203 is scattered.
The degree of scattering is related to a radius of curvature of an
arc and can be controlled by a height h, for example. As the height
h decreases, the degree of scattering decreases, and as the height
h increases, the degree of scattering increases. Meanwhile, as
shown in FIG. 2C, the cross section parallel to the v direction is
rectangular, and if the structure 201 is irradiated with light 204
in an arrow direction, surface reflected light 205 is not
scattered. By printing the structure 201 having a roughness shape
as shown in FIG. 2A on a print medium such as print paper, it is
possible to have different degrees of scattering of light depending
on an illumination direction. The image printing apparatus
according to the present embodiment prints an image representing
anisotropy by laminating and printing a roughness forming material
such as a UV-curable ink and forming the structure 201 having a
roughness shape as shown in FIG. 2A on a print medium.
[0035] Next, a description will be given of a printing method of an
image representing a high-contrast anisotropy. An image
representing a high-contrast anisotropy may be obtained by printing
on a print medium the structure 201 having a large difference
between a degree of scattering of the surface reflected light 203
in the u direction and a degree of scattering of the surface
reflected light 205 in the v direction shown in FIG. 2A to FIG. 2C.
That is, the degree of scattering of the surface reflected light
203 in the u direction is made as high as possible and the degree
of scattering of the surface reflected light 205 in the v direction
is made as low as possible in FIG. 2A to FIG. 2C. To increase the
degree of scattering of the surface reflected light, the height h
of the structure 201 of FIG. 2B may be increased, but in general,
it is difficult to form the structure 201 with a great height h on
the print medium. Even if such a structure can be formed, the
resulting structure 201 may become unnaturally conspicuous.
[0036] In general, ink landed on a print medium is laminated, and
fine roughness is formed on the print medium. At this time, if the
ink lands adjacently in a short period of time on the print medium,
the ink merges as liquid, thereby forming a smooth surface on the
print medium. FIG. 3A is a schematic view for explaining fine
roughness on the surface of the print medium. As shown in FIG. 3A,
an ink droplet landed on a print medium 301 is laminated, and a dot
302 forms fine roughness on the surface of the print medium 301.
The fine roughness formed on the surface of the print medium 301
causes the surface reflected light to be scattered. Such a fine
roughness area formed on the surface of the print medium 301 is an
area having a low smoothness. As shown in FIG. 3B, however, if ink
droplets land adjacently in a short period of time on the print
medium 301, the ink droplet merges with another, thereby forming a
smooth ink layer 303 on the surface of the print medium 301. The
smooth ink layer 303 can reduce scattering of the surface reflected
light. Such a smooth area formed on the surface of the print medium
301 is an area having a high smoothness.
[0037] A conventional image forming apparatus forms a structure
having a shape as shown in FIG. 2A on a print medium to have
different levels of light scattering according to an illumination
direction and forms an image representing anisotropy. However, an
ink droplet landed on the surface of the structure forms fine
roughness, and the formed fine roughness causes the surface
reflected light to be scattered in the v direction (FIG. 2A and
FIG. 2C). As a result, a printed image has a low-contrast
anisotropy. According to the present embodiment, to print an image
reproducing a high-contrast anisotropy, control is performed so
that an ink layer having a high smoothness is formed in a direction
in which scattering of the surface reflected light is preferably
decreased, and an area having a low smoothness is formed by fine
roughness in a direction in which scattering of the surface
reflected light is preferably increased. More specifically, the
image printing apparatus according to the present embodiment prints
an image reproducing a high-contrast anisotropy by performing pass
separation based on anisotropy information and controlling a smooth
area printed in the same pass to be flatter as the degree of
scattering of the surface reflected light increases.
(Schematic Configuration of an Image Printing Apparatus)
[0038] FIG. 4 is a block diagram for explaining a schematic
configuration of an image printing unit 400 of an image printing
apparatus 1 according to the present embodiment. The image printing
unit 400 is an ink jet printer performing image printing by using
ink. A head cartridge 401 has a print head having a plurality of
ejection ports and an ink tank for supplying ink to the print head.
The head cartridge 401 is positioned by a carriage 402 and
replaceably mounted, and the carriage 402 can be reciprocated along
a guide shaft 403. More specifically, the carriage 402 has a main
scanning motor 404 as a driving source and is driven by a driving
mechanism including a motor pulley 405, a driven pulley 406, and a
timing belt 407, and the position and the movement of the carriage
402 are controlled. It should be noted that movement along the
guide shaft 403 of the carriage 402 is referred to as "main
scanning" and a moving direction is referred to as "a main scanning
direction." A print medium 408 such as print paper is loaded into
an auto sheet feeder (hereinafter referred to as "ASF") 410. In
printing an image, a pickup roller 412 is rotated via a gear by
driving of a paper feed motor 411, and the print medium 408 is
separated one by one from the ASF 410 and fed. Further, by the
rotation of a conveying roller 409, the print medium 408 is
conveyed to a print start position opposite to an ejection port
surface of the head cartridge 401 on the carriage 402. The
conveying roller 409 has a line feed (LF) motor 413 as a driving
source and is driven via the gear. Determination on whether the
print medium 408 has been fed and confirmation of a paper feed
position take place when the print medium 408 passes a paper end
sensor 414. The head cartridge 401 mounted on the carriage 402
includes an ink tank which stores ink as a printing material, a
print head which causes ink supplied from the ink tank to be
ejected in response to an ejection signal, and an ultraviolet
radiation device. The print head is held so that the ink ejection
port surface protrudes downward from the carriage 402 to be in
parallel with the print medium 408. Six types of inks, for example,
are used: yellow (Y), magenta (M), cyan (C), black (K), a roughness
forming material (W), and a gloss adjusting material (S). Color
inks of Y, M, C, and K are pigment inks which have substantially
the same refractive index as that of the print medium 408, for
example, and color is reproduced according to the combination of
four types of inks. The roughness forming material is, for example,
a white ultraviolet-curable ink. The roughness forming material
landed on the print medium 408 cures when irradiated with
ultraviolet rays by the ultraviolet radiation device and forms a
structure having a roughness shape on the surface of the print
medium 408. Forming the structure on the print medium 408 can
control the degree of scattering of the surface reflected light
according to an illumination direction and print an image
reproducing anisotropy. The gloss adjusting material is, for
example, a transparent ink having a refractive index that is lower
than those of color inks of Y, M, C, and K. Printing a gloss
adjusting material on the top surface of the image can control an
intensity of reflected light on the surface.
(Image Printing Operation)
[0039] Next, an image printing operation will be described. First,
after the print medium 408 is conveyed to a predetermined print
start position, the carriage 402 moves above the print medium 408
along the guide shaft 403, and ink is ejected from the ejection
ports of the print head during the movement of the carriage 402.
Then, if the carriage 402 moves to one end of the guide shaft 403,
the conveying roller 409 conveys, by a predetermined amount, the
print medium 408 in a direction perpendicular to the scanning
direction of the carriage 402. The conveyance of the print medium
408 is referred to as "paper feed" or "sub-scanning" and a
conveying direction is referred to as "a paper feed direction" or
"a sub-scanning direction." After the conveyance of the print
medium 408 by the predetermined amount, the carriage 402 moves
again along the guide shaft 403. In this manner, repeating the
scanning of the carriage 402 of the print head and paper feed, an
image is printed across the print medium 408. The image printing
unit 400 according to the present embodiment prints an image on the
print medium 408 through two steps: forming a structure having a
roughness shape and printing color and gloss. The structure is
formed by laminating and printing a roughness forming material W.
Every time the printing of one layer is completed, the conveying
roller 409 is rotated backward to return the print medium 408 to
the print start position before going on to the next layer. After
the printing of all layers is completed and the formation of the
structure is completed, printing of color and gloss is started. The
printing of color and gloss according to the present embodiment is
performed by 8-pass printing in which scanning of the print head is
performed eight times on the same line of the print medium 408.
[0040] FIG. 5A to FIG. 5C are schematic views for explaining a
multi-pass printing operation by the image printing unit 400. In
the schematic views of FIG. 5A to FIG. 5C, an operation of 2-pass
printing is shown in which scanning of the print head is performed
twice on the same line of the print medium 408 to print an image.
As shown in FIG. 5A to FIG. 5C, in the case of the 2-pass printing,
image printing is performed corresponding to a width L of the print
head by main scanning of the carriage 402, and every time printing
of one line is finished, the print medium 408 is conveyed in a
sub-scanning direction by a distance L/2. For example, an area A is
printed by M.sup.th main scanning (FIG. 5A) and (M+1).sup.th main
scanning (FIG. 5B) of the print head, and an area B is printed by
(M+1).sup.th main scanning (FIG. 5B) and (M+2).sup.th main scanning
(FIG. 5C) of the print head. In n-pass printing in which an image
is formed by performing main scanning of the print head n times on
the same line of the print medium 408, every time printing of one
line is finished, for example, the print medium 408 is conveyed in
a sub-scanning direction by a distance L/n. In the case of 8-pass
printing, eight kinds of image data consisting of ejection signals
of printing materials, for example, are prepared. In each scanning
of the print head, the printing material is ejected based on the
image data corresponding to the number of scannings. In the
M.sup.th main scanning of the print head, given that a remainder in
the division of M by 8 is K, the printing material is ejected based
on (K+1).sup.th image data. In the following description, printing
in an n.sup.th pass (n: 1 to 7) means printing by main scanning,
where a value K is n, and printing in the 8.sup.th pass means
printing by main scanning, where a value K is 0. Further, pass
separation means processing of determining in which pass, from the
1.sup.st pass to the 8.sup.th pass, a target pixel should be
printed. The determined pass number is referred to as a printing
pass for the target pixel. It should be noted that printing of a
structure for each layer is performed by one pass.
(Hardware Configuration)
[0041] FIG. 6 is a block diagram showing a hardware configuration
which mainly serves for image processing in the image printing
apparatus 1. In FIG. 6, a host 600 which functions as an image
processing unit is a computer, for example, and has a
microprocessor (CPU) 601 and a memory 602 such as a random access
memory. The host 600 also has an input unit 603 such as a keyboard
and an external storage device 604 such as a hard disk drive. The
host 600 further has a communication interface (hereinafter
referred to as "a printer I/F") 605 for communication with the
image printing unit 400 and a communication interface (hereinafter
referred to as "a video I/F") 606 for communication with a monitor
610. The CPU 601 executes various kinds of processing according to
programs stored in the memory 602 and performs image processing of
the present embodiment, in particular, generation of a pass
separation signal, generation of a pass mask, and generation of an
ejection signal. These programs are stored in the external storage
device 604 or provided by an external information processing device
(not shown). The host 600 outputs various kinds of information to
the monitor 610 via the video I/F 606 and inputs various kinds of
information through the input unit 603. The host 600 is connected
to the image printing unit 400 via the printer I/F 605 to transmit
the image-processed ink ejection signal to the image printing unit
400 for printing and receive various kinds of information from the
image printing unit 400.
(Image Printing Procedure)
[0042] FIG. 7 is a flow chart showing an image printing procedure
of the image printing apparatus 1 according to the present
embodiment. The processing through the flow chart of FIG. 7 is
executed by the CPU 601 which loads a program code stored in the
external storage device 604 into the memory 602.
[0043] In S701, image data to be printed is inputted. The image
printing apparatus 1 of the present embodiment inputs image data
including not only RGB color signals, but also a signal specifying
anisotropy. The image data to be inputted includes a signal .phi.
specifying an azimuth angle at which a reflection intensity of
specular reflected light corresponding to incident light becomes a
maximum, a signal gloss1 specifying the reflection intensity of the
specular reflected light in a direction of an azimuth angle .phi.,
and a signal haze1 specifying an intensity of reflected light near
the specular reflection direction. The image data to be inputted
further includes a signal gloss2 specifying the reflection
intensity of the specular reflected light corresponding to the
incident light in a direction orthogonal to the azimuth angle .phi.
and a signal haze2 specifying an intensity of reflected light near
the specular reflection direction. The signal .phi. is, for
example, an angle defined by the y direction in FIG. 1A to FIG. 1D
and an X axis direction of the inputted image data defined by
coordinates on the XY plane, and gloss1 and haze1 respectively
correspond to the length of the line oc and the length of the line
od shown in FIG. 1B. Likewise, gloss2 and haze2 respectively
correspond to the length of the line oa and the length of the line
ob shown in FIG. 1A. In the present embodiment, an angle .alpha.
defined by cod in FIG. 1B and an angle .alpha. defined by aob in
FIG. 1A are 2 degrees, for example. A value of gloss1 is equal to
or greater than a value of gloss2. A value of haze1 is equal to or
less than a value of haze2.
[0044] In S702, the CPU 601 obtains anisotropy information from the
inputted image data. The anisotropy information of the present
embodiment corresponds to the signal .phi., a signal h1, and a
signal h2. The signal .phi. specifies an azimuth angle at which a
reflection intensity of specular reflected light corresponding to
incident light becomes a maximum, and can be obtained from the
inputted image data. Values of h1 and h2 are respectively derived
by the division of haze1 and haze2 specifying an intensity of
reflected light near the specular reflection direction by a total
amount g0 of reflected light near the specular reflection direction
and the normalization of the result. The total amount g0 of
reflected light of the present embodiment is an integral of an
intensity of reflected light in a direction in which an angle
defined with respect to the specular reflection direction is, for
example, 10 degrees or smaller, and corresponds to values specified
by areas 111 and 112 in FIG. 1A and FIG. 1B. The total amount g0 of
reflected light varies depending on the material of the surface on
which the incident light is reflected. In the present embodiment,
h1 and h2 indicate degrees of scattering of the surface reflected
light. As the value increases, the degree of scattering increases.
As the value decreases, the degree of scattering decreases. That
is, as a difference between h1 which indicates the degree of
scattering of the surface reflected light in the y direction in
FIG. 1B and h2 which indicates the degree of scattering of the
surface reflected light in the x direction in FIG. 1A increases,
anisotropy is determined to have higher contrast. Details will be
described with reference to FIG. 10. The same value of h1 and h2
indicates a similar degree of scattering regardless of the material
of the surface.
[0045] The total amount g0 of reflected light is derived by a known
interpolation method with reference to a conversion table based on
gloss1, haze1, gloss2, and haze2 obtained from the image data
inputted in S701. FIG. 8 is a schematic view showing an example of
a conversion table 800 of a total reflected light amount according
to the present embodiment. The conversion table 800 of a total
reflected light amount is a table which describes a signal
specifying the corresponding total amount g0 of specular reflected
light in association with a discrete value of gloss, which is a
signal relating to a reflection intensity of specular reflected
light, and haze, which is a signal relating to an intensity of
reflected light near the specular reflection direction. The CPU 601
refers to the conversion table 800 of a total reflected light
amount and obtains a total amount g of reflected light
corresponding to a combination of gloss1 and haze1 and a total
amount g of reflected light corresponding to a combination of
gloss2 and haze2 by interpolation, and an average of them is set as
a signal g0. Although an intensity of reflected light near the
specular reflection direction changes depending on whether the
surface which is irradiated with light is roughness or smooth, a
total amount of reflected light itself does not substantially
change. Meanwhile, a total amount of reflected light near the
specular reflection direction changes depending on the material of
the surface which is irradiated with light. The image printing
apparatus 1 of the present embodiment controls an amount of a gloss
adjusting material S based on the total amount g0 of reflected
light so as to reproduce the total amount of reflected light near
the specular reflection direction. It should be noted that
regardless of the above value, the total amount g0 of reflected
light may be a total amount of reflected light near the specular
reflection direction corresponding to a combination of an average
of gloss1 and gloss2 and an average of haze1 and haze2. The image
printing apparatus 1 of the present embodiment forms a structure
having a roughness shape based on .phi., h1, and h2 on a print
medium and controls a time difference between ejections of a
printing material on the structure, so that an image reproducing a
high-contrast anisotropy is printed.
[0046] In S703, the CPU 601 generates structure shape data based on
the anisotropy information. The structure shape data of the present
embodiment is data specifying the number of times the roughness
forming material is laminated on a plane of, for example, 16 pixels
in height and 16 pixels in width. First, the CPU 601 refers to a
shape generation table 900 and generates the structure shape data
from h1 and h2. FIG. 9 is a schematic view showing an example of
the shape generation table 900. The shape generation table 900 is a
table which describes a combination of h1 and h2 in association
with the number of times the roughness forming material is
laminated in each block on the plane of 16 pixels in height and 16
pixels in width. In the shape generation table 900, (a,b) indicates
the number of times the roughness forming material is laminated on
a pixel at column a and row b on the plane of 16 pixels in height
and 16 pixels in width. The number of times the roughness forming
material is laminated corresponding to any combination of h1 and h2
can be calculated by a known interpolation method.
[0047] FIG. 10 is a schematic view showing an example of a shape of
a structure formed based on the structure shape data. In FIG. 10,
an X direction, a Y direction, and a Z direction respectively show
a horizontal direction, a vertical direction, and a height
direction in a front view. In a case where values of h1 and h2 are
small, a degree of scattering of surface reflected light is
decreased by forming a structure having a flat shape. For example,
the image printing apparatus 1 forms a structure 1001 having a flat
shape on a print medium based on small values of h1 and h2. In a
case where values of h1 and h2 are large, a degree of scattering of
surface reflected light is increased by forming a structure having
a shape with a large radius of curvature. For example, the image
printing apparatus 1 forms a structure 1002 having a shape with a
large radius of curvature on a print medium based on large values
of h1 and h2. In a case where a difference between h1 and h2 is
large, anisotropy is reproduced by forming a structure having a
shape with different radii of curvature between the X direction and
the Y direction. For example, the image printing apparatus 1 forms
a structure 1003 having a shape with different radii of curvature
between the X direction and the Y direction on a print medium based
on a small value of h1 and a large value of h2. Then, a
predetermined computation is added to the structure shape data, and
structure shape data for specifying a structure rotated by .phi.
degrees on the XY plane in FIG. 10 is further generated. Then, the
CPU 601 generates an ejection signal W(n) of the roughness forming
material W from the number of times the roughness forming material
is laminated in the structure shape data. W(n) represents an
ejection signal of the roughness forming material for forming an
n.sup.th layer.
[0048] In S704, the CPU 601 generates color data and gloss data.
The image printing apparatus 1 of the present embodiment reproduces
color on the print medium by using four types of printing
materials, C, M, Y, and K, and reproduces gloss on the print medium
by using the gloss adjusting material S. The color data is data
specifying arrangement of the printing materials C, M, Y, and K.
The color data of the present embodiment is generated through the
following procedure. First, color signals RGB are obtained from the
image data inputted in S701. Then, with reference to the color
conversion table, the color signals RGB are converted into color
signals R',G',B' which are dependent on the printing apparatus. The
color conversion table is a table which describes the color signals
R',G',B' corresponding to discrete color signals RGB, and each
color signal is converted by using a known three-dimensional
look-up table. The above color conversion allows color specified by
the inputted color signals to be mapped into color reproducible in
the image printing apparatus 1. A plurality of color conversion
tables, such as for minimizing a color difference, giving a higher
priority to chroma, and giving a higher priority to lightness, may
be stored in advance in the memory 602 and the color conversion
table to be used may be switched depending on a purpose. A table to
be used may be determined based on user's selection from the
plurality of color conversion tables. Then, with reference to a
color separation table, the color signals R',G',B' are converted
into signals C,M,Y,K specifying amounts of printing materials. The
color separation table is a table which describes printing material
signals C,M,Y,K corresponding to discrete color signals R',G',B',
and each color signal is converted by using a known
three-dimensional look-up table. To match the structure shape data
with a resolution, one pixel in the inputted image data is divided
into 16 blocks in height and blocks in width, and the same signals
C,M,Y,K are associated with all of 256 blocks in total. Then,
halftone processing is applied to each type of printing material,
and the printing material signals C,M,Y,K are converted into binary
signals C',M',Y',K' indicating whether to arrange a printing
material on each block. The binary signals C',M',Y',K' indicate,
for example, arrangement of the printing material if a value is 1,
and no arrangement of the printing material if a value is 0. For
the halftone processing, a known error diffusion method or ordered
dither method can be used.
[0049] The gloss data is data specifying arrangement of the gloss
adjusting material S. The gloss data of the present embodiment is
generated through the following procedure. First, with reference to
a gloss conversion table, a signal g0 specifying a total amount of
reflected light near the specular reflection direction is converted
into a gloss signal g0' which is dependent on the printing
apparatus. The gloss conversion table is a table which describes
the signal g0 and the gloss signal g0' corresponding to a discrete
value of color signals R',G',B', and the gloss signal is converted
by using a known interpolation method. The above conversion allows
the total amount of reflected light near the specular reflection
direction indicated by the signal g0 to be mapped into a
reproducible range in the image printing apparatus 1. Then, with
reference to a gloss separation table, the gloss signal g0' is
converted into a signal S specifying the amount of a gloss
adjusting material. The gloss separation table is a table which
describes a printing material signal S corresponding to a discrete
gloss signal g0', and the conversion from the gloss signal g0' into
the printing material signal S is performed by using a known
interpolation method. To match the structure shape data with a
resolution, one pixel in the inputted image data is divided into 16
blocks in height and 16 blocks in width, and the same signal S is
associated with all of 256 blocks in total. Then, halftone
processing is applied to the printing material signal S, and the
printing material signal S is converted into a binary signal S'
indicating whether to arrange a printing material on each block.
The binary signal S' indicates, for example, arrangement of the
printing material if a value is 1, and no arrangement of the
printing material if a value is 0. For the halftone processing, a
known error diffusion method or ordered dither method can be
used.
[0050] In S705, the CPU 601 performs pass separation on the color
data and gloss data consisting of binary signals C',M',Y',K',S' and
generates ejection signals C'',M'',Y'',K'',S'' of the printing
materials. The pass separation of the present embodiment is
performed by using a pass mask generated based on anisotropy
information. In this example, the pass mask is binary data
generated one for each pass. In the present embodiment, eight
pieces of binary data are generated corresponding to eight passes.
The pass separation is processing of calculating an OR between a
binary signal of each printing material and each pass mask and
generating an ejection signal corresponding to each pass. For
example, based on the binary signal C' and a pass mask for the
1.sup.st pass, image data for output consisting of the ejection
signal C'' for the 1.sup.st pass of the printing material C is
generated. The ejection signal C'' is set to 1 indicating ejection
of the printing material if both the binary signal C' and a value
of a corresponding pixel in the pass mask are 1. The ejection
signal C'' is set to "0" indicating no ejection of the printing
material if either of the binary signal C' and the value of the
corresponding pixel in the pass mask is 0. In general, an image
size of the pass mask is smaller than a size of a target image to
be printed on the print medium, but in the present embodiment, the
pass mask is repeatedly arranged in height and width and applied.
Details of a method for generating a pass mask, which is a main
part of the present embodiment, will be described later. It should
be noted that pass separation is not needed for the structure shape
data because each layer of the laminate structure is printed in one
pass.
[0051] In S706, the CPU 601 controls the image printing unit 400 to
print an image on a print medium. The image printing unit 400
laminates and prints the roughness forming material based on the
structure shape data generated in S703 to form a structure having a
roughness shape. Then, based on the ejection signals
C'',M'',Y'',K'',S'' of the printing materials, the printing
materials C, M, Y, K, and S are ejected on an upper surface of the
formed structure having a roughness shape to print color and gloss.
In the present embodiment, a description has been given of an
aspect of printing the printing materials on the upper surface of
the formed structure having a roughness shape, but without forming
a structure having a roughness shape, anisotropy may be reproduced
only by printing color and gloss by controlling a time difference
between ejections of a printing material.
(Procedure for Generating a Pass Mask)
[0052] FIG. 11 is a flow chart showing a procedure for generating a
pass mask according to the present embodiment. With reference to
the flow chart of FIG. 11, the procedure for generating a pass mask
will be described. In S1101, the CPU 601 generates a first pass
separation pattern based on h2, which is the anisotropy
information. In this example, the pass separation pattern is image
data consisting of 16 pixels in height and 16 pixels in width, for
example, and each pixel in the pass separation pattern includes
pass separation signals p1 to p8. The pass separation signal p1
indicates a probability of printing a target pixel in the 1.sup.st
pass. In the same manner, the pass separation signal pn indicates a
probability of printing the target pixel in the n.sup.th pass. Each
pass separation signal is a value not less than 0 and not greater
than 1, and the sum of the pass separation signals p1 to p8 is
1.
[0053] Next, with reference to the schematic view of FIG. 12A to
FIG. 12C, the first pass separation pattern will be described. FIG.
12A is a schematic view showing an example of the first pass
separation pattern corresponding to the case where h2, which is the
anisotropy information, is a minimum, and shows an arrangement
pattern of a printing material printed on the upper surface of the
roughness shape of the structure 1001 in FIG. 10. A minimum value
of h2 is set as h2_0. A first pass separation pattern 1210 includes
four types of patches 1201 to 1204, each including 2 pixels in
height and 2 pixels in width, and the patches having the same type
are not arranged adjacent to one another. The arrangement pattern
of the four types of patches is repeated vertically and
horizontally, and a sign 1203(a) and a sign 1203(b) continuously
form one patch 1203. In the first pass separation pattern 1210
corresponding to the case where the value of h2 is the minimum,
pixels forming the patch 1201 include pass separation signals in
which only the pass separation signal p1 is "1." That is, pixels
included in the patch 1201 are printed in the 1.sup.st pass. In the
same manner, pixels forming the patches 1202, 1203, and 1204
include pass separation signals in which only the pass separation
signals p2, p3, and p4 are "1," respectively. Pixels included in
the patches 1202, 1203, and 1204 are printed in the 2.sup.nd,
3.sup.rd, and 4.sup.th passes, respectively. In patch areas divided
by the patches 1201 to 1204, a printing material is printed in the
same pass. The printing material printed in the same pass forms a
smooth surface as shown in FIG. 3B. The smooth surface formed by
the printing material printed in the same pass is referred to as a
smooth area. An image on which pass separation is performed by the
first pass separation pattern 1210 has a smooth area having the
same height and width, that is, 2 pixels in height and 2 pixels in
width. More specifically, since the smooth area is formed to have
the same height and width, an aspect ratio of the smooth area
decreases. As a result, the image on which pass separation is
performed by the first pass separation pattern 1210 becomes an
image having a low-contrast anisotropy, in which a reflection
characteristic does not change depending on a direction of incident
light or an observation direction. It should be noted that the
aspect ratio in the present embodiment is a value obtained by a
mathematical expression 1-(b/a), where a is a maximum width of an
area in a longer axial direction and b is a minimum width of the
area in a shorter axis direction.
[0054] FIG. 12B is a schematic view showing an example of a first
pass separation pattern corresponding to the case where h2, which
is the anisotropy information, is a maximum, and shows an
arrangement pattern of a printing material printed on the upper
surface of the roughness shape of the structure 1003 in FIG. 10. A
maximum value of h2 is set as h2_1. A first pass separation pattern
1220 includes four types of patches 1205 to 1208, each including 4
pixels in height and 1 pixel in width, and the patches having the
same type are not arranged adjacent to one another. The arrangement
pattern of the four types of patches is repeated vertically and
horizontally, and a sign 1207(a) and a sign 1207(b) continuously
form one patch 1207. In the first pass separation pattern 1220
corresponding to the case where the value of h2 is the maximum,
pixels forming the patch 1205 include pass separation signals in
which only the pass separation signal p5 is "1." That is, pixels
included in the patch 1205 are printed in the 5.sup.th pass. In the
same manner, pixels forming the patches 1206, 1207, and 1208
include pass separation signals in which only the pass separation
signals p6, p7, and p8 are "1," respectively. Pixels included in
the patches 1206, 1207, and 1208 are printed in the 6.sup.th,
7.sup.th, and 8.sup.th passes, respectively. Patch areas divided by
the patches 1205 to 1208 each form a smooth area, in which a
printing material is printed in the same pass. An image on which
pass separation is performed by the first pass separation pattern
1220 has a smooth area having different height and width, that is,
4 pixels in length and 1 pixel in width. More specifically, since
the smooth area is formed to have the different height and width,
an aspect ratio of the smooth area increases. As a result, the
image on which pass separation is performed by the first pass
separation pattern 1220 becomes an image having a high-contrast
anisotropy, in which a reflection characteristic changes depending
on a direction of incident light or an observation direction.
[0055] FIG. 12C is a schematic view showing an example of the first
pass separation pattern corresponding to the case where a value of
h2, which is the anisotropy information, is h2_0<h2_2<h2_1. A
first pass separation pattern 1230 corresponding to the case where
h2 is h2_0<h2_2<h2_1 is a pass separation pattern formed by
writing the patches 1205 to 1208 of the first pass separation
pattern 1220 over the first pass separation pattern 1210. The
number of patches 1205 to 1208 written over the first pass
separation pattern 1210 is variable, and increases from 0 to 64
according to an increase in the value of h2, from h2_0 to h2_1. It
should be noted that the pass separation pattern matches with the
first pass separation pattern 1210 if the value of h2 is h2_0 and
matches with the first pass separation pattern 1220 if the value of
h2 is h2_1. An image on which the pass separation is performed by
the first pass separation pattern 1230 also has an anisotropy
contrast which is variable depending on the number of patches to be
overwritten.
[0056] In S1102, the CPU 601 generates a second pass separation
pattern based on h1, which is the anisotropy information. More
specifically, the CPU 601 generates a second pass separation
pattern by writing a patch for diffusing printing passes over the
first pass separation pattern generated in S1101. FIG. 13 is a
schematic view showing an example of the second pass separation
pattern. A second pass separation pattern 1300 shown in FIG. 13 is
a pass separation pattern formed by writing a patch 1301 including
1 pixel in height and 1 pixel in width over the first pass
separation pattern generated in S1101. Pixels forming the patch
1301 include pass separation signals in which the pass separation
signals p1 to p8 are equally "0.125." That is, all of the pixels
forming the patch 1301 are printed in any one of the 1.sup.st pass
to the 8.sup.th pass with the same probability. Further, in a case
where the probability of being printed in each pass is equal, the
printing pass is determined so that pixels printed in the same
scanning of the print head are diffused. In many cases, therefore,
adjacent pixels are printed in different passes. The number of
patches 1301 to be overwritten increases from 0 to 255 according to
an increase in the value of h1, from a minimum h1_0 to a
predetermined value h1_1. In a case where the number of patches
1301 to be overwritten is small, like the patch 1208 in the second
pass separation pattern 1300, the number of areas in which adjacent
pixels are printed in the same pass relatively increases.
Meanwhile, in a case where the number of patches 1301 to be
overwritten is large, due to the patches 1301 arranged in the
second pass separation pattern 1300, the number of areas in which
adjacent pixels are printed in the same pass relatively decreases.
That is, controlling the arrangement of the patches 1301 to be
overwritten can control a ratio between the number of areas printed
in the same pass and the number of areas printed in different
passes. It should be noted that the second pass separation pattern
matches with the first pass separation pattern if the value of h1
is h1_0, and matches with a pattern in which all pixels are formed
of the patches 1301 if the value of h1 is equal to or greater than
h1_1. A pattern of the printing material printed on the upper
surface of the roughness shape of the structure 1002 of FIG. 10
corresponds to a pattern in which all pixels are formed of the
patches 1301.
[0057] In S1103, the CPU 601 performs a computation to rotate by
.phi. degrees the second pass separation pattern 1300 generated in
S1102 based on a signal .phi. and generates a third pass separation
pattern. In the present embodiment, pass separation signals of the
third pass separation pattern can be obtained in the following
manner, for example. First, a position (i2,j2) in the second pass
separation pattern 1300 corresponding to the pixel at row i3 and
column j3 of the third pass separation pattern (i3,j3:0, 1, . . . ,
15) is obtained by the following equation (1):
( i 2 j 2 ) = ( cos .phi. sin .phi. - sin .phi. cos .phi. ) ( i 3 -
7 j 3 - 7 ) + ( 7 7 ) ( 1 ) ##EQU00001##
[0058] The equation (1) shows a content of a computation to rotate
the third pass separation pattern by -.phi. degrees around the
pixel at column 7 and row 7 of the third pass separation pattern.
The pass separation signals at row i3 and column j3 of the third
pass separation pattern correspond to the pass separation signals
at row i2 and column j2 of the second pass separation pattern 1300.
However, since values of i2 and j2 calculated by the equation (1)
in general are not integers, it is needed to calculate pass
separation signals corresponding to the pixel at row i2 and column
j2 of the second pass separation pattern 1300. The pass separation
signals can be calculated by linear interpolation as follows, for
example. First, a largest integer not greater than i2 is set as
i_min, a smallest integer greater than i2 is set as i_max, a
largest integer not greater than j2 is set as j_min, and a smallest
integer greater than j2 is set as j_max. Furthermore, each of
i_min, i_max, j_min, and j_max is divided by 16, and their
respective remainders are set as i_min', i_max', j_min', and
j_max'. For example, if i_min is -1, i_min' is 15. Values of
i_min', i_max', j_min', and j_max' are obtained from the range
between 0 and 15. Next, a pass separation signal p_i2_jmin(n) at
row i2 and column j_min of the second pass separation pattern 1300
is obtained by the following equation (2):
p_i2_jmin(n)=.alpha..sub.i.times.p_imin_jmin(n)+.beta..sub.i.times.p_ima-
x_jmin(n) (2)
[0059] Incidentally, p_imin_jmin(n) indicates an n.sup.th pass
separation signal of the pixel at row i_min' and column j_min' of
the second pass separation pattern 1300. In the same manner,
p_imax_jmin(n) indicates an n.sup.th pass separation signal of the
pixel at row i_max' and column j_min' of the second pass separation
pattern 1300. Further, parameters .alpha.i and .beta.i are obtained
by the following equations (3) and (4):
.alpha..sub.i=(i_max-i.sub.2)/(i_max-i_min) (3)
.beta..sub.i=(i.sub.2-i_min)/(i_max-i_min) (4)
[0060] Next, a pass separation signal p_i2_jmax(n) at row i2 and
column j_max of the second pass separation pattern 1300 is obtained
by the following equation (5):
p_i2_Jmax(n)=.alpha..sub.i.times.p_Imin_Jmax(n)+.beta..sub.i.times.p_Ima-
x_Jmax(n) (5)
[0061] Note that p_imin_jmax(n) indicates an n.sup.th pass
separation signal of the pixel at row i_min' and column j_max' of
the second pass separation pattern 1300. In the same manner,
p_imax_jmax(n) indicates an n.sup.th pass separation signal of the
pixel at row i_max' and column j_max' of the second pass separation
pattern 1300. Finally, a pass separation signal p_i2_j2(n) at row
i2 and column j2 of the second pass separation pattern 1300 is
obtained by the following equation (6):
p_i2_j2(n)=.alpha..sub.j.times.p_i2_jmin(n)+.beta..sub.j.times.p_i2_jmax-
(n) (6)
[0062] Note that parameters .alpha.j and .beta.j are obtained by
the following equations (7) and (8):
.alpha..sub.j=(j_max-j.sub.2)/(j_max-j_min) (7)
.beta..sub.j=(j.sub.2-j_min)/(j_max-j_min) (8)
[0063] This p_i2_j2(n) is a pass separation signal of the pixel at
row i3 and column j3 (i3,j3:0, 1, . . . , 15) of the third pass
separation pattern. According to the equation (6), pass separation
signals of each pixel of the third pass separation pattern can be
obtained from the pass separation signals of the pixel of the
second pass separation pattern 1300. For all of the pixels of the
third pass separation pattern, pass separation signals are obtained
by the above equations (1) to (8). It should be noted that the
processing in step S1103 is not limited to the above method. For
example, a known two-dimensional interpolation method and the like
may be used. The third pass separation pattern becomes data forming
a pass mask according to a value of a signal .phi.. The image
printing apparatus 1 of the present embodiment performs control
such that a longitudinal direction of a smooth area in which a
printing material is printed with a small time difference becomes
the same as a direction indicated by the signal .phi..
[0064] Next, in S1104, the CPU 601 generates a pass mask based on
the pass separation signals of the third pass separation pattern
and determines a pass in which each pixel of image data for output
is printed. The pass mask of the present embodiment is image data
consisting of 16 pixels in height and 16 pixels in width like the
pass separation pattern, and one piece of image data is generated
for each pass, that is, eight pieces of image data in total. A
pixel forming each pass mask includes a binary signal pn'(n:1, 2, .
. . , 8) indicating whether or not to eject a printing material in
a corresponding pass. For example, p1' indicates a signal of a pass
mask for printing the 1.sup.st pass. In pass mask generation
processing, pixels are sequentially processed from an upper left
pixel in the pass mask to the right one by one, and if the
processing on the right end pixel is finished, the processing moves
to the left end pixel in a row immediate below. All pixels are
sequentially processed in the same manner to the lower right pixel.
The pass mask is generated by using a known error diffusion method,
for example.
[0065] FIG. 14 is a flow chart showing a procedure for generating a
pass mask from the third pass separation pattern. In S1401, the CPU
601 selects an upper left pixel of the third pass separation
pattern as a first pixel to be processed.
[0066] In S1402, the CPU 601 calculates evaluated pass separation
signals obtained by the addition of error signals from adjacent
pixels to pass separation signals of a target pixel. For example,
it is assumed that pass separation signals of the target pixel are
(p1,p2,p3,p4,p5,p6,p7,p8)=(0,0,0.5,0.5,0,0,0,0) and error signals
are (0,0,0,0.3,0,0,0,0). In this case, the evaluated pass
separation signals are (0,0,0.5,0.8,0,0,0,0).
[0067] In S1403, the CPU 601 selects a maximum from the evaluated
pass separation signals p1 to p8, and a pass mask for a
corresponding pass is set to 1, and pass masks for other passes are
set to 0. In the above example, the maximum among the evaluated
pass separation signals p1 to p8 is 0.8 which corresponds to p4.
Accordingly, a signal p4' of the 4-pass pass mask is set to 1 and
signals p1',p2',p3',p5',p6',p7',p8' of the 1- to 3-pass and 5- to
8-pass pass masks are set to 0. In a case where there are a
plurality of maximums among the evaluated pass separation signals
p1 to p8, one of them is selected to make the above settings.
[0068] In S1404, the CPU 601 calculates error signals and diffuses
them to adjacent pixels. The error signals are obtained by the
subtraction of pass separation signals corresponding to the pass
selected in S1403 from the above evaluated pass separation signals.
In the above example, the selected pass is the 4.sup.th pass, and
the corresponding pass separation signals are (0,0,0,1,0,0,0,0) and
error signals are (0,0,0.5,-0.2,0,0,0,0). FIG. 15 is a schematic
view for explaining a mechanism of diffusing error from a target
pixel of pass mask generation processing to the adjacent pixels. In
the schematic view of FIG. 15, Q0 indicates a target pixel for the
pass mask generation processing, and an area with oblique lines
shows a processed pixel on which a printing pass has already been
determined. Error of the target pixel Q0 is diffused at a
predetermined ratio to pixels Q1, Q2, Q3, and Q4 which are adjacent
to Q0 and on which a pass signal has not been determined. For
example, error signals 7/16, 3/16, 5/16, and 1/16 of Q0 are
diffused to the pixels Q1, Q2, Q3, and Q4. If the probability of
being printed in each pass is equal, the adjacent pixels have a
lower probability of being printed in a pass determined to be a
printing pass because negative error signals are diffused to the
adjacent pixels. As a result, pixels printed in the same pass are
determined to be diffused.
[0069] In S1405, it is determined whether processing has been
performed on all pixels. If there is an unprocessed pixel, a target
pixel for the pass mask generation processing is updated and the
process returns to step S1402. If processing has been performed on
all pixels, the processing is finished.
(Functional Configuration)
[0070] FIG. 16 is a block diagram showing a functional
configuration of an image printing apparatus according to the
present embodiment. The input unit 603 inputs RGB color signals. In
addition to the RGB color signals, the input unit 603 inputs a
signal .phi. specifying an azimuth angle at which a reflection
intensity of specular reflected light corresponding to incident
light becomes a maximum, a signal gloss1 specifying the reflection
intensity of the specular reflected light in an azimuth angle
.phi., and a signal haze1 specifying a reflection intensity of
diffused light near the specular reflection direction. Further, the
input unit 603 inputs a signal gloss2 specifying the reflection
intensity of the specular reflected light corresponding to the
incident light in a direction orthogonal to the azimuth angle .phi.
and a signal haze2 specifying a reflection intensity of diffused
light near the specular reflection direction. An anisotropy
information obtaining unit 1601 performs the processing of S703 in
the image printing procedure of FIG. 7. That is, the anisotropy
information obtaining unit 1601 calculates signals g0, h1, and h2
from gloss1, gloss2, haze1, and haze2. A shape data generating unit
1602 performs the processing of S703 in the image printing
procedure of FIG. 7. That is, the shape data generating unit 1602
refers to the shape generation table 900 stored in a shape
generation table storage unit 1610 and generates an ejection signal
W(n) of a roughness forming material from the signals .phi., h1,
and h2.
[0071] A color/gloss conversion unit 1603, a printing material
separation unit 1604, and a halftone processing unit 1605 perform
the processing of S704 in the image printing procedure of FIG. 7.
That is, the color/gloss conversion unit 1603 refers to a color
conversion table and a gloss conversion table stored in a
color/gloss conversion table storage unit 1611 and calculates color
signals R',G',B' which are dependent on the printing apparatus and
a gloss signal g0' from the signals RGB and g0. The printing
material separation unit 1604 refers to a color separation table
and a gloss separation table stored in a color/gloss separation
table storage unit 1612 and calculates signals C,M,Y,K,S specifying
amounts of printing materials from the color signals R',G',B' and a
gloss signal g'. The halftone processing unit 1605 calculates
binary signals C',M',Y',K',S' specifying arrangement of printing
materials from the signals C,M,Y,K,S specifying amounts of printing
materials.
[0072] A pass separation signal generating unit 1606 performs the
processing of S1101 to S1103 in the pass mask generation processing
of FIG. 11. That is, pass separation signals p1 to p8 of the third
pass separation pattern are calculated from the signals .phi., h1,
and h2. A pass mask generating unit 1607 performs the processing of
S1104 in the pass mask generation processing of FIG. 11. That is,
the pass separation signals p1 to p8 of the third pass separation
pattern are binarized, and signals p1' to p8' forming a pass mask
for each pass are calculated. An ejection signal generating unit
1608 performs the processing of S705 in the image printing
procedure of FIG. 7. That is, the ejection signal generating unit
1608 performs pass separation on binary signals C',M',Y',K',S' by
using a pass mask for each pass and generates ejection signals
C'',M'',Y'',K'',S'' for each pass. An image printing processing
unit 1609 performs the processing of S706 in the image printing
procedure of FIG. 7. That is, a roughness forming material is
laminated and printed on a print medium based on shape data W(n) to
form a structure having a roughness shape. The image printing
processing unit 1609 further ejects each printing material on the
upper surface of the formed structure having a roughness shape
based on the ejection signals C'',M'',Y'',K'',S'' to print color
and gloss.
[0073] FIG. 17 is a view showing an exemplary output image from the
image printing apparatus 1 according to the present embodiment. An
output image 1620 of the present embodiment is schematically shown
as an example outputted on the print medium 408 in a case where a
value of h1 is 0.4, a value of h2 is 0.8, and a value of .phi. is
45 degrees. The output image 1620 is an image formed on the print
medium 408 by the image printing processing unit 1609 based on the
ejection signals C'',M'',Y'',K'',S'' for each pass generated by the
ejection signal generating unit 1608.
[0074] A first area 1626 is an area formed by a printing material
adjacently ejected in an azimuth angle .phi. direction in the same
scanning of the print head. Since the printing material lands
adjacently in a short period of time, the landed printing material
forms a high-smoothness area in the first area 1626. As a result,
the first area 1626 has a low degree of scattering with respect to
incident light 1621 from the .phi. direction and has a high degree
of scattering with respect to a direction orthogonal to the .phi.
direction. As described above, such control of ejection signals for
each pass is performed by the signals p1' to p8' forming a pass
mask for each pass generated by the pass mask generating unit 1607.
A first structure 1627 is a structure having a roughness shape
formed based on the shape data W(n) generated by the shape data
generating unit 1602. The image printing processing unit 1609
prints the first structure 1627 based on the shape data W(n) so as
to have a shape having different radii of curvature between the
.phi. direction and the direction orthogonal to the .phi.
direction. Since the radius of curvature in the .phi. direction is
small and the radius of curvature in the direction orthogonal to
the .phi. direction is large, the first structure 1627 has a low
degree of scattering with respect to the incident light from the
.phi. direction and has a high degree of scattering with respect to
the direction orthogonal to the .phi. direction. Accordingly, in a
case where the incident light 1621 from the .phi. direction and an
observation direction 1622 are in the relation of regular
reflection, a reflection intensity of the first area 1626 becomes
higher than that in a case where incident light 1623 from the
direction orthogonal to the .phi. direction and an observation
direction 1624 are in the relation of regular reflection. As a
result, the first area 1626 is viewed as lighter, with a higher
gloss, than a second area 1628. In the present embodiment, the
first area 1626 printed in the same pass is formed on the upper
surface of the first structure 1627. By matching a scattering
property of the structure 1627 with a scattering property of the
area 1626 printed on the upper surface thereof, a high-contrast
anisotropy can be exhibited.
[0075] The second area 1628 is an area formed by a printing
material adjacently ejected in the azimuth angle .phi. direction by
a plurality of different scannings of the print head. Since a
printing material lands at some time intervals, the landed printing
material is laminated in the second area 1628 to form a
low-smoothness area having fine roughness. As a result, the second
area 1628 has a high degree of scattering regardless of the
direction of the incident light. As described above, such control
of ejection signals for each pass is performed by the signals p1'
to p8' forming a pass mask for each pass generated by the pass mask
generating unit 1607. A second structure 1629 is a structure having
a roughness shape formed based on the shape data W(n) generated by
the shape data generating unit 1602. The image printing processing
unit 1609 prints the second structure 1629 based on the shape data
W(n) so as to be large in size with the same radius of curvature
between the .phi. direction and the direction orthogonal to the
.phi. direction. Since a radius of curvature is large regardless of
the direction, the second structure 1629 has a high degree of
scattering regardless of the direction of the incident light.
Accordingly, in a case where the incident light and the observation
direction are in the relation of regular reflection, a reflection
intensity in the second area 1628 is substantially the same
regardless of whether the incident light is the incident light 1621
from the .phi. direction or the incident light 1623 from the
direction orthogonal to the .phi. direction.
[0076] In the present embodiment, in a case where the incident
light 1621 from the .phi. direction and the observation direction
1622 are in the relation of regular reflection, a specular
reflection intensity in the first area 1626 becomes relatively
higher than that in the second area 1628. As a result, the first
area 1626 is viewed as lighter, with a higher gloss, than the
second area 1628. Meanwhile, as illustrated in FIG. 1A to FIG. 1D,
in a case where the observation direction 1622 is a direction
slightly shifted from the specular reflection direction (for
example, by a degrees in FIG. 1A to FIG. 1D), the first area 1626
viewed as lighter and the second area 1628 viewed as darker are
reversed. More specifically, the first area 1626 is viewed as
darker than the second area 1628. The output image 1620 of the
present embodiment is formed as described above, and therefore, it
is possible to print an image reproducing anisotropy such as gloss
and color which vary depending on the incident light or observation
direction.
[0077] As described above, based on the inputted image data, the
image printing apparatus 1 of the present embodiment obtains
anisotropy information including an azimuth angle .phi. at which a
reflection intensity of specular reflected light becomes a maximum
and h1 and h2 specifying degrees of scattering of surface reflected
light. The image printing apparatus 1 determines a time difference
between ejections of a printing material based on the obtained
anisotropy information and generates an ejection signal of the
printing material for generating an image. The image printing unit
400 ejects the printing material on the print medium with a time
difference of a predetermined threshold or less to form a smooth
area on the print medium. The above configuration allows the image
printing apparatus 1 of the present embodiment to print an image
reproducing high anisotropy.
Modification Example 1
[0078] The image printing apparatus 1 of the first embodiment
applies control of an ejection time difference based on the
obtained anisotropy information to all of the printing materials C,
M, Y, K, and S which reproduce color and gloss. In a modification
example 1, a description will be given of an image printing
apparatus 1 which applies control of an ejection time difference
based on anisotropy information only to specific printing
materials.
[0079] The image printing apparatus 1 of the modification example 1
divides the printing materials into a group of two light color
printing materials Y and S and a group of three dark color printing
materials C, M, and K and applies the control of an ejection time
difference based on anisotropy information only to the group of two
light color printing materials Y and S. In the control of an
ejection time difference as described in the first embodiment,
ejecting a printing material in the same pass allows the printing
material arranged adjacently to merge, thereby forming a smooth
surface on a print medium. However, when the printing material
merges, a printing position at which the printing material lands on
the print medium slightly changes, which may be exhibited as
granular noise or stripes. In this case, applying the control of an
ejection time difference only to the light color printing
materials, which make the granular noise or stripes less visible,
can preferably print an image reproducing anisotropy. An ejection
signal generating unit 1608 of the modification example 1 uses a
pass mask generated in a pass mask generating unit 1607 and
performs pass separation on color data and gloss data respectively
consisting of binary signals Y',S'.
[0080] Meanwhile, the ejection signal generating unit 1608 performs
pass separation on color data consisting of binary signals C',M',K'
not depending on anisotropy information, but by using a pass mask
for performing control such that pixels printed in the same
scanning by a print head are diffused and arranged. As an example
of such a pass mask, it is possible to use a pass mask used by the
ejection signal generating unit 1608 in a case where a value of h1
is equal to or greater than h1_1 in the first embodiment, for
example. This pass mask will be hereinafter referred to as a
diffusion pass mask. In an image printing procedure of the
modification example 1, in ejection signal generation processing
(S705), pass separation is performed on the printing materials Y
and S by using a pass mask generated based on anisotropy
information. Meanwhile, pass separation is performed on the
printing materials C, M, and K by using the diffusion pass mask to
generate an ejection signal for each pass. A description of other
features will be omitted since they are the same as those in the
first embodiment.
[0081] As described above, the image printing apparatus of the
present modification example determines a time difference between
ejections of a specific type of printing material based on
anisotropy information and, based on the determined time
difference, generates an ejection signal of the specific type of
printing material. According to the above feature, the image
printing apparatus 1 of the present embodiment can print an image
reproducing high anisotropy without making the granular noise or
stripes easily visible.
Modification Example 2
[0082] In the present modification example, a description will be
given of an image printing apparatus 1 which applies control of an
ejection time difference based on anisotropy information only to a
printing material used for printing a surface layer of an image.
The image printing apparatus 1 of the modification example 2 uses
two types of printing materials that are colorless and transparent
for controlling gloss. More specifically, in addition to the gloss
adjusting material S, a gloss adjusting material T is used. One of
these two types of printing materials is printed on a surface layer
of an image to exhibit any gloss. The control of an ejection time
difference as described in the first embodiment is applied only to
the two types of printing materials S and T but not to the other
printing materials C, M, Y, and K. Performing the control of an
ejection time difference based on anisotropy information only on
the printing material used for printing a surface layer of an image
can omit processing based on anisotropy information for the
printing materials other than the gloss adjusting materials S and
T, and reduce processing load on the image printing apparatus 1.
Material having a refractive index lower than that of color ink is
used for the gloss adjusting material S, and material having a
refractive index higher than that of color ink is used for the
gloss adjusting material T.
[0083] An ejection signal generating unit 1608 of the modification
example 2 uses a pass mask generated in a pass mask generating unit
1607 to perform pass separation on gloss data consisting of binary
signals S',T'. Meanwhile, the ejection signal generating unit 1608
performs pass separation on color data consisting of binary signals
C',M',Y',K' by using a diffusion pass mask. Further, a printing
material separation unit 1604 of the modification example 2 refers
to a gloss separation table to convert a signal g0' into signals
S,T specifying amounts of the gloss adjusting materials. The gloss
separation table is a table which describes gloss printing
materials S and T corresponding to a discrete gloss signal g0' and
uses a known interpolation method. In this example, to match
structure shape data with a resolution, a pixel of inputted image
data is divided into 16 blocks in height and 16 blocks in width,
and the same signals S,T are associated with all of 256 blocks in
total. Gloss printing material signals S and T respectively
represent a probability of printing a target area by the gloss
adjusting material S and a probability of printing the target area
by the gloss adjusting material T, and the sum of the probabilities
is 1. In a block having a small signal g0', more pixels are printed
by the gloss adjusting material S which has a low refractive index
so as to decrease a reflected light amount. That is, the gloss
separation table describes a small signal g0' in association with a
large gloss printing material signal S and a small gloss printing
material signal T. Meanwhile, in a block having a large signal g0',
more pixels are printed by the gloss adjusting material T which has
a high refractive index so as to increase a reflected light amount.
That is, the gloss separation table describes a large signal g0' in
association with a large gloss printing material signal T and a
small gloss printing material signal S.
[0084] Furthermore, from the gloss printing material signals S,T, a
halftone processing unit 1605 of the present modification example
generates a binary signal S' specifying whether to arrange the
gloss adjusting material S or the gloss adjusting material T in
each block. The binary signal S' indicates, for example,
arrangement of the gloss adjusting material S if a value is 0 and
arrangement of the gloss adjusting material T if a value is 1. That
is, either the gloss adjusting material S or the gloss adjusting
material T is printed on the surface layer of the image. In the
present modification example, in the halftone processing, the
processing method of the pass mask generation processing (S1104) of
the first embodiment is used. That is, a CPU 601 generates an
evaluated signal by the addition of an error signal from adjacent
areas to a gloss printing material signal of a target area, and
then compares an S component and a T component of the evaluated
signal to control the printing material corresponding to the
component having a larger value to be arranged in the target area.
Then, an error signal is obtained by the subtraction of 1 from a
value of the component corresponding to the printing material to be
arranged, of the components of the evaluated signal, and is
diffused to the adjacent pixels.
[0085] Next, an image printing processing unit 1609 of the present
modification example first laminates and prints a roughness forming
material W based on shape data W(n) to form a structure having a
roughness shape. Then, on an upper surface of the formed structure
having a roughness shape, color is printed based on ejection
signals C'',M'',Y'',K''. Then, a conveying roller 409 is rotated
backward to return a print medium 408 to a print start position to
print gloss by ejecting the gloss adjusting material S or the gloss
adjusting material T based on the ejection signal S' on the color
printed image. In an image printing procedure of the present
modification example, in S704, the color/gloss conversion unit 1603
described in the first embodiment and the printing material
separation unit 1604 and the halftone processing unit 1605 of the
modification example 2 are used to obtain a binary signal
specifying arrangement of each printing material. Further, in the
ejection signal generation processing (S705), pass separation is
performed on the printing materials S and T by using a pass mask
generated based on anisotropy information like the first
embodiment. Meanwhile, pass separation is performed on the printing
materials C, M, Y, and K by using a diffusion pass mask not
depending on anisotropy information. In image printing (S706), the
image printing processing unit 1609 of the modification example 2
first laminates and prints the roughness forming material W to form
a structure having a roughness shape, then color is printed by the
printing materials C, M, Y, and K, and finally gloss is printed by
the printing materials S and T. A description of other kinds of
processing will be omitted since they are the same as those in the
first embodiment.
[0086] As described above, the image printing apparatus of the
present modification example determines a time difference between
ejections of a printing material used for printing a surface layer
of an image based on anisotropy information and, based on the
determined time difference, generates an ejection signal of the
printing material used for printing the surface layer of the image.
According to the above feature, the image printing apparatus 1 of
the present embodiment can print an image reproducing high
anisotropy while reducing processing load.
Modification Example 3
[0087] In the present modification example, an image printing
apparatus 1 receives a printing condition setting and controls a
time difference between ejections of a printing material based on
the received printing condition and anisotropy information. The
image printing apparatus 1 of the present modification example will
be described.
[0088] FIG. 18 is a schematic view showing an example of a UI (User
Interface) 1700 which receives a printing condition setting. The UI
1700 of the present modification example is displayed, for example,
on a monitor 610, and receives a user operation via an input unit
603. The UI 1700 of the present modification example includes an
anisotropy emphasis processing checkbox 1701, to-be-processed ink
setting checkboxes 1702 to 1706, and pattern selection radio
buttons 1707 and 1708. The UI 1700 also includes an OK button 1709
and a cancel button 1710, and a sign 1711 indicates a mouse cursor.
A user can select each checkbox and each button by operating the
mouse cursor 1711. The anisotropy emphasis processing checkbox 1701
receives a printing condition setting indicating whether to perform
control of a time difference between ejections of a printing
material. If selection of the checkbox 1701 is inputted, selection
of the checkboxes 1702 to 1706 and the radio buttons 1707 and 1708
becomes available. If the anisotropy emphasis processing checkbox
1701 is unchecked, the checkboxes 1702 to 1706 and the radio
buttons 1707 and 1708 are grayed out, and selection by the mouse
cursor 1711 becomes unavailable. The to-be-processed ink setting
checkboxes 1702 to 1706 are checkboxes for setting a printing
material to be processed. The checkboxes 1702 to 1706 are
respectively associated with printing materials C, M, Y, K, and S,
and if a checkbox is checked, the corresponding printing material
is set as a printing material to be processed. If the checkbox is
unchecked, the corresponding printing material is excluded from a
printing material to be processed. For example, in a case where the
checkboxes 1704 and 1706 and the checkboxes 1702, 1703, and 1705
are unchecked, the printing materials Y and S are set as printing
materials to be processed.
[0089] The pattern selection radio buttons 1707 and 1708 are radio
buttons for receiving a setting input of a patch shape used in a
first pass separation pattern. If the radio button 1707 is
selected, a patch having 2 pixels in height and 2 pixels in width
is set to a shape with a small aspect ratio which is used for low
anisotropy, and a patch having 4 pixels in height and 1 pixel in
width is set to a shape with a large aspect ratio which is used for
high anisotropy. If the radio button 1708 is selected, a patch
having 4 pixels in height and 4 pixels in width is set to a shape
with a small aspect ratio which is used for low anisotropy, and a
patch having 16 pixels in height and 1 pixel in width is set to a
shape with a large aspect ratio which is used for high anisotropy.
As the initial setting of the UI 1700, the radio button 1707 is
being selected, and if a selection input to the radio button 1708
is received, a selection input to the radio button 1707 is
released. In contrast, if a selection input to the radio button
1707 is received while the radio button 1708 is selected, a
selection input to the radio button 1708 is released. If a
selection input to the OK button 1709 is received, printing
conditions received by the input to each checkbox and each radio
button are confirmed. If a selection input to the cancel button
1710 is received, printing conditions received by the input to each
checkbox and each radio button are cancelled, and the printing
conditions before receiving the setting are maintained.
[0090] In the present modification example, a pass separation
signal generating unit 1606 and an ejection signal generating unit
1608 perform processing based on the set and received printing
conditions. In a case where control of an ejection time difference
is not performed, the processing by the pass separation signal
generating unit 1606 and a pass mask generating unit 1607 of the
present modification example is skipped. Then, the ejection signal
generating unit 1608 of the present modification example performs
pass separation by using a diffusion pass mask not depending on
anisotropy information. Meanwhile, in a case where control of an
ejection time difference is performed, the pass separation signal
generating unit 1606 of the present modification example generates
a first pass separation pattern with a set patch shape.
[0091] Then, the pass mask generating unit 1607 of the present
modification example generates a pass mask based on the set patch
shape. In a case where control of an ejection time difference is
performed, the ejection signal generating unit 1608 of the present
modification example performs pass separation on the printing
material set as a printing material to be processed among binary
signals C',M',Y',K',S' by using the pass mask generated in the pass
mask generating unit 1607. On the printing material not set as a
printing material to be processed among the binary signals
C',M',Y',K',S', pass separation is performed by using a diffusion
pass mask not depending on anisotropy information. In an image
printing procedure of an image printing apparatus 1 of the present
modification example, a printing condition setting is received
before ejection signal generation processing (S705). For example, a
printing condition setting using the UI 1700 is received before
performing a data input (S701). As described above, in the image
printing procedure of the present modification example, the
ejection signal generating unit 1608 performs pass separation on
the printing material set as a printing material to be processed
among the binary signals C',M',Y',K',S' by using a pass mask
generated in the pass mask generating unit 1607 (S705). A
description of other features will be omitted since they are the
same as those in the first embodiment.
[0092] As described above, the image printing apparatus 1 of the
present modification example further includes a receiving unit
receiving a printing condition setting, determines a time
difference between ejections of a printing material based on
anisotropy information and a printing condition, and generates an
ejection signal of the printing material based on the determined
time difference and printing condition. According to the above
feature, the image printing apparatus 1 of the present embodiment
can print an image reproducing high anisotropy under an optimum
printing condition for a user.
Second Embodiment
[0093] In the present embodiment, a description will be given of an
image printing apparatus of a type which prints an image by using a
plurality of print heads, not a type which prints an image by
reciprocating scanning of a print head.
[0094] FIG. 19 is a block diagram showing a schematic configuration
of an image printing unit 1800 of the present embodiment. The image
printing unit 1800 is an ink jet printer having a plurality of
print heads. Print heads 1801 to 1808 individually have ejection
units for ejecting five types of printing materials C, M, Y, K, and
S, and print color and gloss on a print medium by ejection of the
printing materials from the ejection units. The print heads 1801 to
1808 are long heads having a size in a direction vertical to a
paper surface greater than a width of the print medium. One line in
the direction vertical to the paper surface is printed without the
scanning of each print head. Further, there is a sufficient
distance between the print heads so that an ink droplet printed by
adjacent print heads does not merge. The printing material ejected
from the ejection unit included in the same print head is ejected
with a small ejection time difference from the ejection unit, and
the printing material merges as soon as it lands on the print
medium, thereby forming a smooth surface. Meanwhile, the printing
material ejected from the ejection units included in different
print heads is ejected with a great ejection time difference from
the ejection units. Thus, the printing material does not merge even
if it lands adjacently on the print medium. Accordingly, it does
not form a smooth surface.
[0095] The image printing apparatus 1 of the present embodiment
determines which print head is used to eject each printing material
based on anisotropy information, so as to control a time difference
between printings of a printing material arranged adjacently. A
description will be given with reference to FIG. 19. A print medium
408 loaded on a paper feed tray 1811 is fed by individual rotations
of a paper feed roller 1812, a conveying roller 1813, and a
separation roller 1814, and the fed print medium 408 is
electrostatically adsorbed on a conveying drum 1815. The conveying
drum 1815 rotates in an arrow direction shown in FIG. 19. The
conveying drum 1815 rotates so that the print medium 408 adsorbed
by the conveying drum 1815 passes an area opposite to a print head
1809 predetermined times. The print head 1809 ejects a roughness
forming material W at a timing at which the print medium 408 passes
the front of the print head 1809. Then, an ultraviolet radiation
device 1810 irradiates the roughness forming material W ejected on
print medium 408 with ultraviolet rays to cure the roughness
forming material W. The print head 1809 laminates and prints the
roughness forming material W on the print medium 408 to form a
structure having a roughness shape. For example, the print head
1809 prints a first layer at a first timing at which the print
medium 408 passes the area opposite to the print head 1809, and
after the conveying drum 1815 further rotates once, prints a second
layer at a timing at which the print medium 408 passes the area
opposite to the print head 1809 next time. In the case of forming a
roughness shape having a laminate structure of 100 layers, the
conveying drum 1815 rotates 100 times with the print medium 408
adsorbed on the conveying drum 1815. If formation of the structure
having a roughness shape is completed, the print medium 408 is
separated from the conveying drum 1815 by a drum separation lug
1816 and then electrostatically adsorbed on a conveying belt 1817.
The conveying belt 1817 rotates in the arrow direction shown in
FIG. 19. The conveying belt 1817 allows the print medium 408
adsorbed on the conveying belt 1817 to pass the area opposite to
the print heads 1801 to 1808. The print heads 1801 to 1808
individually eject five types of printing materials C, M, Y, K, and
S at a timing at which the print medium 408 passes the area
opposite to the print heads 1801 to 1808. The print heads 1801 to
1808 eject the printing materials on the print medium 408, and the
print medium 408 on which color and gloss are thus printed is
separated from the conveying belt 1817 by a belt separation lug
1818 and outputted onto an output tray 1819.
[0096] A pass separation signal generating unit 1606, a pass mask
generating unit 1607, and an ejection signal generating unit 1608
of the second embodiment generate signals specifying the print
heads 1801 to 1808 ejecting the printing materials instead of
ejection signals C'',M'',Y'',K'',S'' for each pass. A pass
separation signal p1 generated by the pass separation signal
generating unit 1606 indicates a probability of printing a target
pixel by the print head 1801, not a probability of printing the
target pixel in the 1.sup.st pass. Likewise, pass separation
signals p2 to p8 indicate probabilities of printing the target
pixel by the print heads 1802 to 1808. A pass mask generated by the
pass mask generating unit 1607 is a mask for determining a print
head printing the target pixel. The ejection signal generating unit
1608 generates ejection signals for the print heads 1801 to 1808.
The processing in an image printing processing unit 1609 of the
second embodiment is performed by the image printing unit 1800.
Descriptions of other features and the image printing procedure
will be omitted since they are the same as those in the first
embodiment.
[0097] As described above, the image printing apparatus 1 of the
present embodiment has a plurality of print heads and generates an
ejection signal for each print head based on the obtained
anisotropy information. According to the above feature, the image
printing apparatus 1 of the present embodiment can print an image
reproducing high anisotropy.
Other Embodiments
[0098] In the above embodiments, information specifying an azimuth
angle .phi. at which a reflection intensity of specular reflected
light corresponding to incident light becomes a maximum and
information specifying degrees of scattering near the specular
reflection direction in a .phi. direction and a direction
orthogonal to .phi. are set as anisotropy information. However, the
configuration of the anisotropy information is not limited to the
above. For example, the anisotropy information may be information
including reflection intensities of a plurality of specular
reflected lights or may be information on a plurality of gloss
mappings or information including a plurality of reflection hazes.
A reflection intensity of specular reflected light may be a
20-degree specular reflection glossiness, a 60-degree specular
reflection glossiness, or other angles. The anisotropy information
is not limited to an azimuth angle at which a reflection intensity
of specular reflected light becomes a maximum and a direction
orthogonal to the azimuth angle. For example, the anisotropy
information may be information on 360 degrees azimuth by 1 degree.
The anisotropy information may also be a value by a BRDF
(bidirectional reflectance distribution function) which samples a
direction of light and an observation direction with respect to a
predetermined azimuth angle and an elevation angle. In the
embodiments, a description has been given of the configuration of
printing an image by moving the print head relative to the print
medium, but a configuration of printing an image by moving the
print medium relative to the print head may also be used.
[0099] In the embodiments, a description has been given of the
configuration of not applying the control of a time difference
between ejections of a printing material to a roughness forming
material, but the control may be applied to the roughness forming
material. For example, in the case of forming a roughness shape
with different radii of curvature between directions, a plurality
of passes are designed to print each layer of a laminate structure,
and pass separation is performed so that a longer axial direction
of an area printed in the same pass matches with a direction with a
smaller radius of curvature. According to the above feature,
roughness in the direction with a smaller radius of curvature
decreases, and roughness in the direction with a larger radius of
curvature increases, allowing reproduction of higher
anisotropy.
[0100] The present invention can also be applied to an image
printing apparatus not having a function of forming a structure
having a roughness shape. In this case, color and gloss are printed
on a print medium on which a structure having a roughness shape is
formed in advance, by controlling a time difference between
ejections of a printing material based on anisotropy information.
Alternatively, without forming a structure having a roughness
shape, anisotropy may be reproduced only by printing color and
gloss on which control is performed of a time difference between
ejections of a printing material. The number of passes, the number
of lamination, the size of a pass separation pattern, a patch
shape, and the like are not limited to the configurations of the
embodiments. The types of printing materials are not limited to the
configurations of the embodiments, either. The present invention
may have light color inks or special colors such as metallic, red,
green, and light orange.
[0101] In the embodiments, a description has been given of the
configuration in which the host performs processing until
generation of an ejection signal and the image printing unit
performs printing processing based on the ejection signal, but the
share of the processing steps is not limited to this. The host may
perform processing until the processing of calculating signals
C,M,Y,K,S specifying amounts of printing materials by the printing
material separation unit 1604, and the image printing apparatus may
perform the pass mask generation processing and the halftone
processing, and the processing thereafter. Alternatively, the image
printing apparatus may perform all kinds of processing. The
processing of the color/gloss conversion unit 1603 or the
processing of the printing material separation unit 1604 may be
changed according to shape data generated in the shape data
generating unit 1602. For example, depending on the shape data, the
color conversion table and the color separation table may be
switched, or an output signal may be corrected depending on the
shape data. According to the above configurations, an influence of
shape on change in color and gloss may be suppressed.
[0102] Embodiment(s) of the present invention can also be realized
by a computer of a system or apparatus that reads out and executes
computer executable instructions (e.g., one or more programs)
recorded on a storage medium (which may also be referred to more
fully as a `non-transitory computer-readable storage medium`) to
perform the functions of one or more of the above-described
embodiment(s) and/or that includes one or more circuits (e.g.,
application specific integrated circuit (ASIC)) for performing the
functions of one or more of the above-described embodiment(s), and
by a method performed by the computer of the system or apparatus
by, for example, reading out and executing the computer executable
instructions from the storage medium to perform the functions of
one or more of the above-described embodiment(s) and/or controlling
the one or more circuits to perform the functions of one or more of
the above-described embodiment(s). The computer may comprise one or
more processors (e.g., central processing unit (CPU), micro
processing unit (MPU)) and may include a network of separate
computers or separate processors to read out and execute the
computer executable instructions. The computer executable
instructions may be provided to the computer, for example, from a
network or the storage medium. The storage medium may include, for
example, one or more of a hard disk, a random-access memory (RAM),
a read only memory (ROM), a storage of distributed computing
systems, an optical disk (such as a compact disc (CD), digital
versatile disc (DVD), or Blu-ray Disc (BD).TM.), a flash memory
device, a memory card, and the like.
[0103] According to the present invention, it is possible to
provide image data representing an image which reproduces higher
anisotropy as compared to a conventional method.
[0104] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0105] This application claims the benefit of Japanese Patent
Application No. 2015-123012, filed Jun. 18, 2015, which is hereby
incorporated by reference herein in its entirety.
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